Sheet clamp



April 8, 1941. M. G. BARKER S HEET CLAN P Filed Dec. 24, 1940 INV ENTOR. 1742/ G flung-em ATTORNEY.

v "It is a further .together and to adjoining Patented Apr. 8, 1941UNITED STATES PATENT OFFICE v12 Claims.

This invention relates to fastening devices, more particularly 'todevices for temporarily holding assemblies together while permanentfastening means such as rivets or other fasteners are applied.

In the fabrication of structures involving a large number of driven orheaded fasteners, such as the sheet metal construction employed inaeroplanes, it is often necessary to provide some temporary fasteningmeans for holding the sheets structural members while rivets are beingdriven. Due to the extent of the parts held together, ordinary c clampscannot be used, and recourse is had to the rivet holes and some means isprovided for engaging the rivet holes and drawing the material togetherwhile it is being riveted. At the present time, the most common type offastener for this purpose involves a body member having a pair ofprojecting elements one being slidable and engageable under the shoulderof the hole and which is drawn inwardly by a spring to cause the-sheetsto be drawn together. This type of holder requires special applyingforceps, and in addition is extremely fragile as the projecting element,which is machined from the body member, often breaks oi! during use orapplication. The force which is available for drawing the sheet metaltogether is limited by the type of g spring used to retract the slidingelement and the size bi'the body of the holder, Accordinsly. there is avery deiinite limit upon the cl ping force which can'be made availablein a h der of given size.

7 1 th the above considerations in mind, it is an object of the presentinvention to provide a temporary fastener which can be readily insertedwithout the use of special tools.

It is a further object of the present invention to provide a fastenerwhich readily fastens in holes through different thicknesses ofmaterial.

It is a further object of the present invention to provide a fastenerwhich will force the members being secured with sufficient compressive'force to insure accuracy while riveting.

' It is a further object of the present invention to provide a fasteningelement which can be readily adapted to holes of diflerent diameters.

object of this invention to provide a fastening element which is alwaysin position ready to insert in place.

-It is a further object of the present invention to provide a holderwhich is rugged and not susceptible to breakage.

It is a further object of the present invention to provide a holderwhich does not depend upon accurately machined surfaces for itsefflciency.

It is a further object of the present invention to provide a holder, thework-engaging elements of which can be fashioned of wire of high tensilestrength.

'It is a further object of the present invention to provide a holderwhich automatically locks in place.

It is a further object of the present invention to provide a holder inwhich the work-engaging elements can be readily renewed.

It is a further object of this invention to provide a device which willalign the holes on the material being clamped during the clampingoperation.

This invention possesses many other advantages and has other objectswhich may be made more easily apparent from a consideration of oneembodiment of the invention. For this purpose there is shown a form inthe drawing accompanying and forming part of the present specification.This form will now be described in detafl, illustrating the generalprinciples of the invention; but it is to'be understood that thisdetailed description is not to be taken in a limiting sense, since thescope of the invention is defined in the appended claims.

Referring to the drawing:

i Figure 1 is a side elevation of one form of a device embodying thepresent invention shown inserted in the work but in unclamped position;

Figure 2 is a top plan view of the device shown vin Figure 1;

- Figure 3 is a vertical sectional view taken along line 3-3 of Figure 2showing the device in clamped position, and also showing in dot and dashlines the parts in another stage of operation; and

Figure 4 is a transverse section taken as indicated by line 4-4 oiFigure 3.

It is proposed in the present device to provide a clamp which, afterinsertion, and while the material is being clamped, will first, alignthe holes and then clamp the sheets together. Accuracy of alignment canbe secured in the usual .type of sheetholding clamp only by making theclamp accurately. fit the hole, which means that the machine work onsuch a clamp must be quite accurate and a large number of sizes ofclamps must be provided to iit different sized holes. If

accuracy of the clamp is depended upon to align the holes the clamp mustbe worked about in the holes in an eflort to align the holes, and, asthe material being clamped is often quite soft, such treatment may bendthe material or injure the edges of the holes. In order to accomplishthe above aligning and clamping operation, he present construction isemployed. Figure 1 shows the clamp in position in holes in two sheetswhich are in contact with each other but which are not accuratelyaligned. In Figure 3 the device is shown clamped, and it will be seenthat the holes are now accurately aligned, This result is achieved bycausing the two legs of the clamping element to spread as they sliderelative to each other. The member I is intended to remain stationary inthe device while the member II is mounted for sliding movement and ismoved by means hereinafterdescribed. Member II has a protuberance I2near its outer end and beyond the protuberance it is providedwith anextension I3. As member II is drawn upwardly the extension I 3 strikingthefend of member I 0 causes the members I0 and II to separate. Thisseparation will,of course, align the holes. The holes being in properalignment, further movement of the member II will cause the abutment ofthe protuberance I2 against the edge of the hole in the lower sheet andwill clamp the two sheets together and thus prevent movement in anydirection. The two members III and II are shown so separated in Figure3. With this type of action it never becomes necessary to ream the holesi after the clamp is withdrawn in order that the holes may be used forriveting purposes.

In order that the device be rugged and capable of manufacturewithout'either the member ID or II being accurately machined, it isproposed to make these members I II and II 01' commercially availablesteel wire which has characteristics of durability and strength tarsurpassing any commercially available machinable material. It is alsocontemplated that the members I 0 and ll be readily replaceable in theclamp if one or the other be broken or bent under the vicissitudes 01'use. In the achievement of these and other results the operatingmechanism shown has been devised. A body member I4 and a lever member I5are provided and correlated with the rest oi the structure so thatmovement of the lever member IS with respect to the body member I4causes motion or the locking stem II while of difierent thicknesses.

the pilot III remains stationary, thus drawing the work against the bodymember Il, as above described. Body member Il may be suitablyconstructed of sheet material bent to form a bearing surface It which isprovided with an aperture I! for the reception of the pilot and lockingstem. This hole I'I should be slightly larger than the diameter of thewire utilized for the members I 0 and II in order that the spreading ofthe outer ends caused by the extension I 3 can cause the aligning of theholes in the work. It.is further provided with an upwardly extendingportion I8 suitably formed to be grasped by the lingers in causingrelative movement between the lever I5 volves nothing more than theremoval and replacement oi the pivot I9. The pilot has been illustratedas being made of round material with its operating suriace simplyreduced to a semicircular cross-section by grinding.

In order that the motion of the lever I5 cause motion of the lockingstem I I a link 2| is pivoted to the lever I5 and to a part of thelocking stem II. In the shown form the link 2I is illustrated as achannel having its flanges perforated for the reception of a pivot 22which also passes through the flanges of the lever I5. The stem II issecured to the link 2I by simply having a portion 23 which passesthrough the flanges of link With the aboveconstruction, mere closing ofthe two members I4 and I5 will cause upward movement of the locking stemI I. However, it is desired that the device be capable of remainingclosed'when in clamping position, and further, that the device becapable of use in work In order to accomplish these results, the deviceis so constructed and arranged that upon closing movement the pivot 22passes through a line drawn from pivot I9 to pivot 23. If this is doneit can be readily seen that the device will tend to remain closed as thepivot 22 will have passed the dead center position. This result,however, can be achieved only if some means is provided for producing atension on the pivot 23 in a downward direction. In order to-producethisatension the coil spring 24 is made a part of. the locking stem.When the device is closed to the position shown in the dot and dashlines in Figure 3- the protuberance I2 is against the bottom edge of thehole in thework and further movement of the lever I5 merely causes thespring 24 to be coiled, thus pro- Irom the material ofwhich-the body I4is made. bent down. to the position shown in Figure 3 and provided witha suitable opening to receive the stem II. In order to provide asuitable bearing to take up thethrust oi the link 2| while the device isbeing closed to clamping position the spring 24 may be allowed to rideupon the interior oi. the handle I8 of the body I4.

The above described device is completely operative, but in order to movethe device from the position shownin Figure 3 to that shown in Figure 1a spring 26 is provided which extends around the pivot 22 and engagesthe lever I5 and the body I4. The lever I! may be likewise.

constructed of sheet material bent into a channel shape for strength andto provide means for the attachment of pivots which are part of theoptrating mechanism. The lever I5 is pivoted to' the body ll by means ofa stud or rivet I9 passing through the sides oi the lever I5 and thebody I4, respectively. The pivot I9 forms a satisfadtory point ofattachment for the pilot III. This pilot may be formed ofwire and have aloop 20 at one end thereot through which the pivot I0 can be inserted tohold the pilot inplace. Renewal or replacement of the pilot thus inandthe link 2|. This spring 26 causes the device to normally open, but isof insufllcient strengtli to overcome the closing force exerted byspring 24 when the device is clamped in position in a hole. On the otherhand, if the device is not inserted in the holes, closing of the leverI5 w'lll not cause the spring 24 to be operated and thus the device,except when in place, always remains open. This is a great conveniencein view of the large number of these devices used in a typical assemblyoperation.

I claim:

1. A hole engaging clamp comprising, a pair of elements adapted to beinserted in a hole extending through the members to be clamped, meanscausing relative axial movement between said elements, and means causingseparation of said elements'upon such movement, whereby said elementsare forced against the walls of the hole.

2. A hole engaging clamp comprising, a pair oi elements adapted tobe'inserted in a hole extending through the members to be clamped withthe end of one of said elements in advance of the other, means causingrelative axial movement between said elements, and a projection on saidone element en aging the other element upon such axial movement andcausing separation or said elements to force them into engagement withthe walls of the hole. 1

3. A hole engaging clamp comprising, a pair of elements of substantiallysemi-circular crosssection arranged with their flat sides opposedto eachother and adapted to be inserted in a hole extending through the membersto be clamped, means causing relative axial movement of said elements,and a projection on one of said elements engaging the other element uponsuch movement and causing separation 01 said elements to force them intoengagement with the walls oi the hole.

4. A hole engaging clamp comprising a'pair of elements having opposedflat sides and curved hole engaging sides, and arranged with the end ofone of said elements normally in advance oi the end of the other forinsertion into a hole extending through the members to be clamped, meanscausing relative axial movement of said elements to cause the ends ofthe two elements to pass each other, and a projection on the end of saidone element for engaging the other element upon such movement, wherebyto separate said elements and force them into engagement with the wallsof the hole.

5. A hole engaging clamp comprising, a pair of elements having opposedflat sides and curved hole eng i g sides, and arranged with the end ofone of said elements normally in advance of the end oi the otherfor'insertion into a hole extending through the members to be clamped.means causing retrograde motion of said one element after insertion ofsaid elements into the hole to cause the ends of the elements to passeach other, and a projection in that portion of said one element whichis in advance of the end connecting, said lever and said element tocause motion of said element upon movement of said of the other, saidprojection engaging the other element upon such motion, whereby toseparate said elements and force them into engagement with the walls ofthe hole.

6, A clamp for clamping sheets through holes therethrough comprising, abody, an element projecting from said body, means causing clamp- .hgaction between said element and said body upon movement of said elementtoward said body, a lever on said body, and resilient means operativelyconnecting said element to said lever for motion upon movement of saidlever but permitting yielding of said element with respect to said leveroperatively connecting said element to said lever for such movement,said connecting" link in response to movement of said lever, the pointof connection or said link and saidlever passing through a line drawnbetween the pivot of the lever and the point of attachment of said linkto said member in one stage of operation.

8. A clamp for clamping sheets through holes therethroughcomprising, abody, an element projecting from said body for insertion in holes in thesheets, means causing clamping action oetween said element and said bodyupon movement of said element toward said body, a lever pivoted to saidbody, a link pivoted to, and con-- necting, said lever and said element,resilient means on said element permitting yielding of the pivotalconnection of said link to said element with respect to the projectingportion of said element, the pivotal connection of said link to saidlever passing through a line extending from the lever pivot to thepivotal connection of the link to the element at one stage of operation.

9. A clamp for clamping sheets through holes therethrough comprising, abody, an element projecting from said body for insertion in holes in thesheets, means causing clamping action between said element' and saidbody upon movement of said element toward said body, a lever pivoted toSaid body. a link pivoted to, and connecting, said lever and saidelement, resilient means on said element permitting yielding between thepivotal connection of said link to said element and the projectingportion of said element, the pivotal connection of said link .to saidlever passing through a line extending from the lever pivot to thepivotal connection of the link to the element at one stage of operation,and spring means normally causing motion of said lever to project saidelement from said body, but iheil'ective to cause such motion afterpassage of said pivot connecting the link to the lever through the abovementioned line during clamping while said element is inserted in holesin sheets to be clamped.

10. A clamp for clamping sheets through holes therethrough comprising, abody, a pair of resilient elements projecting thereirom, one of saidelements having its end normally in advance of the end of the other,said one element having a projection in the portion beyond said otherelement, means causing retrograde movement of said one element afterinsertion oi said elements in the holes in the sheets, said movementcausing clamping action between said projection and said 11. Aclamp torclamping sheets through holes therethrough comprising, a body, anelement projecting from said body tor insertion in holes in the sheets,means causing clamping action between said element and said body uponmovement 01 said element toward said body, a lever pivoted to said body,a link pivoted to the lever, a spring connecting said link to theprojecting element and permitting yielding 0! said link with respect tothe projecting element, and a guide on said body e ing said springrestraining its motion during clamping operation of the lever.

12. A clamp for clamping sheets through holes therethrough comprising, abody, a pairot resilient elements projecting therefrom, one 01' saidelements having a projection thereon, means causing retrograde movementof said one element in the holes in the sheets, such movement causingclamping action between said proiection and said man. 0. BARKER.

CERTIFICATE OF CORRECTION. Patent No. 2,257,807. April 8, 19141. MERRILLc. BARKER.

It is hereby certified that errorappears in the printed specification ofthe above numbered patentrequiring correction as follows: Page 5, firstcolunm, lines 65, 66 and 67, claini 6, strike out the words operatiyelyconnecting said element to said lever for such movement, said connectingmeans.'

including resilient means"; and that the said Letters Patent should beread with this correction therein that the same may conform to therecord of the case in the Patent Office.

Signed and sealed this 29th day of July, A. D. 19in.

Henry Van Arsdale (Seal) Acting Commissioner of Patents.

